Require API Version per Request

[bryanculver]

Pynautbot should require the specification of desired API version for all requests (either via environment variable or config) and not use whatever Nautobot specifies as the default. This would move Pynautobot to adhere to the best practice defined in Nautobot's REST API documentation: https://docs.nautobot.com/projects/core/en/stable/rest-api/overview/#default-versions-and-backward-compatibility

[jvanderaa]

Are we thinking that we need to require the api_version key when initiating a pynautobot object? @bryanculver

If that is the case, I believe that may add in some complications as far as getting started with the library. I am going to object on requiring it until there is an easy way to know what API version to use. For just getting started with the library, this adds in a complication.